Revamp work is a significant portion of factory and plant engineering activities. Factories and plants are constantly updating processes and revamping production practices to meet new product demands, EPA regulations, and to replace worn out equipment. As a result, architects and engineering firms have to design equipment that can interface with existing plant conditions. For example, a new process may require interfacing with hundreds or even thousands of existing pipe runs. In order to design the equipment—primarily piping—measurements must be made of the existing factory or plant.
Existing design drawings are not good enough for this task for three primary reasons:                1. They cannot be found or do not exist due to poor record keeping        2. The drawings are pre-CAD and all measurements must be manually interpreted        3. The plant construction does not match the design to the tolerances required for the refit work.Measuring the existing conditions of an operating plant is considered to be:        1. Dangerous. The plant cannot be shut down for measurement work so dangerous conditions exist ranging from moving equipment to hot equipment to exposure to caustic substances. In addition, much of what must be measured is high in the air or otherwise inaccessible.        2. Expensive. Field measurement requires sending a crew of workers to the site for an extended period of time. This is expensive due to man-hour costs on site, lost productivity, travel and lodging expenses, and costs of labor associated with plant personnel required for escort functions.        3. Slow. Current measurement techniques are measured in units of weeks and months. This can seriously impact production schedules. Each day a plant is not operating represents lost production capacity that can never be recovered, and lost profits that can never be realized.        4. Inaccurate. Mistakes in measurement, or the inability to measure parts of the plant, account for serious costs in construction change orders and rework.        
Existing techniques for performing as-built measurement include manual methods using tape measures and plumb bobs, traditional survey techniques, photogrammetry (which is metrology using stereo photograph pairs—often used in aerial surveying and more recently used for process plant measurement), and most recently laser measurement using scanned laser radar systems.
Manual techniques are extremely slow, cumbersome, and dangerous due to needs for hands-on measurement. They are also subject to error and cannot reliably deliver the accuracy required by the engineering profession (+/−¼ inch). Manual techniques for our purposes comprise those techniques which employ traditional measurement tools including tape measures, plumb bobs, rules, and sketch pads.
Traditional survey techniques are useful for ground-based structures but are slow and require a very specialized work process to achieve good results. In addition, the number of data points that can be affordably measured is very small due to the labor-intensive nature of the techniques. Errors can be hard to detect but can drastically influence the outcome due to the small amounts of data gathered. For the purpose of this document, traditional survey techniques comprise the set of techniques that utilize theodolites, laser total stations, retro-reflective targets, and other support equipment that is commonly used by industrial and land surveyors.
Photogrammetry can be more accurate than manual methods and more comprehensive than traditional survey techniques but is very slow and cumbersome. This technique utilizes registered pairs of photographs to triangulate distances from the cameras to points on the surfaces of the plant structures. Photogrammetry relies on an accurate traditional ground survey in order to develop scale, and takes weeks to months for post data collection processing to produce useable results.
Laser radar (also called lidar) is the newest measurement technique to be applied to plant measurement. With this technique a laser is scanned across a volume of space and distances to the surfaces of objects are computed based on the properties of the returning laser beam. Typically the set of points generated by the lidar device is processed using mathematical algorithms into models that can be utilized by traditional CAD software.
The present invention is comprised of a lidar device but with unique properties that enable useful structural data to be generated faster and with a completely different paradigm than other lidar systems.